The present invention relates to apparatus for use in foaming polymeric materials in-place, more particularly the present invention relates to an apparatus, which commprises a movable form for the application of foamed polymeric materials to either a vertical or other surface, such as roof.
Foamed-in-place materials, such as polyurethane are widely used principally for preparing in-place insulations. Currently, almost all commercial applications of such in-place foams is done by means of spraying the polymeric foam onto the surface to be coated with a hand held nozzle. Using prior technology, the foamed in-place material may be sprayed onto a substantially flat surface such as a non-pitched roof or, with care may be sprayed onto a pitched roof or vertical surface, provided the polymer selected has a very short curing time. Sprayed foams are widely used however, spraying requires a high degree skill by the operator. Less skilled operators may produce sprayed layers of uneven thickness. Where thick insulation, e.g., of three to 20 inches is required on a surface, multiple sprayed layers may be applied to the desired thickness. Skilled operators may be able to apply layers of three inch thickness, whereas less skilled operators may be able to spray layers only one or two inches thick. The thinner layers result is a more costly application because of the greater density of the surface (skin) of the foam. The ambient atmosphere into which the foam is sprayed, i.e., temperature, moisture, wind and the like, may adversely effect the foam quality. In multiple layer applications the condensation of moisiture on the skin of lower layers can result in the destruction of foam cell structure and delamination of the layers.
Foamed-in-place materials may also be applied to surfaces which are vertical by means of removable forms. The removable form for one particular structure may be satisfactory, however very few structures are duplicates of other structures, and as a result each application using a foamed-in-place form must be custom job and can be very expensive. Frequently, the foamed material is injected between two wall surfaces, this however, results in uneven foam which is not inspectable because of the structures.
In those applications such as roofing where sprayed polymeric material is presently used to a large extent, the resulting surface is very frequently described as orange peel through popcorn, that is the surface exposed to the air has a rough, uniform texture, about the same texture as the outside of an orange through a popcorn appearance. Furthermore, it has been found that this prior art manner of application results in far more than the theoretical amount of foam being applied to the surface resulting in material waste. In theory, for example, polyurethane foams should produce approximately 6 board feet per pound of material, whereas in actual practice, only about 3 board feet per pound are achieved.
It is frequently necessary that the foams be coated with a material, in order to provide a completely waterproof surface and to protect them, for example from the exposure to the outside environment. In the prior practice, this requires a separate application wherein a coating material, such as sheet or sprayed solutions of butyl rubber, is bonded over a polyurethane foamed-in-place roofing or other installation.
One attempt to overcome the problems of the prior practice for application of foamed-in-place insulation, is described by E. H. Garis in U.S. Pat. No. 3,548,453. The Garis apparatus comprises a self contained unit which is movably mounted to a structure, such as a steel tank, which had spacer studs on which the movable apparatus rests and a traveling foam nozzle mounted on the apparatus so that foam is spread between the studs and on the tank while at the same time a roll of sheet metal is mounted in the apparatus to unroll and press against the foamed material forming a permanent outer surface and providing a form in which the foam expands.
The nature of the foamed material is such that it will usually adhere to the surface of the tank and to the unrolled metal film applied on the outside surface over the foam, thus forming a securely held outer surface. This process was repeated around the tank until the space between the studs had been filled with foamed material and covered with the sheet metal. The Garis process is described as being useful either for vertical application or longitudinal application around the circumference of the tank. This procedure has been applied, however, some problems have developed with regard to the difference in the expansion properties of the foamed polymeric material and the tank studs as well as the metal and there has been some splitting of the seams. A particular disadvantage of this system, however, is the necessity of the sheet metal applied to the outer surface of the foamed material, which in effect is a part of the moveable form and which becomes a structural part of the tank. The use of any other materials than sheet metal, employing the Garis device would not provide the strength necessary to contain the foam which is continuing to rise within the form created by the fixed tank wall, the studs and the sheet metal applied over the studs adjacent to the foamed material.
Various other methods of forming "plastic" materials are shown in U.S. Pat. Nos. 2,522,116; 3,093,232; 3,497,579; 3,475,217; 3,555,131; 3,562,370; 3,691,003; and 3,715,417.
It is a feature of the present invention that a sheet material may be applied to the foam to provide an outer surface coating, but it need not be so applied. It is a particular feature that the coating material is not a structural element and is not necessary to contain the foam. It is a particular feature of the present invention that no studs or spacers as taught in the prior art are required. These features and the method by which they are achieved will be more fully understood from the following discussion including the description of specific embodiments of the invention as setforth in the drawings.